Was going to do a benchmark on it for the caches disabled spreadsheet (and to compare to others) but I have no idea whether the onboard video would be equal to isa, pci, or something in between. I'm guessing a 486/50 would add about 50% performance?
wrote:Was going to do a benchmark on it for the caches disabled spreadsheet (and to compare to others) but I have no idea whether the onboard video would be equal to isa, pci, or something in between. I'm guessing a 486/50 would add about 50% performance?
Hard to tell from what I've found. It could be 'something in between'. According to this the graphics chip is 'local bus', so it could be Compaq's proprietary bus but I've found little evidence to support that it's not just ISA. The Tseng chip it uses was made especially for this machine, it seems.
Also, clock speed increases are rarely (if ever) proportional to any performance increase, particularly where ISA graphics are concerned. The speed of the ISA bus (8MHz) would remain the same, even though the CPU's computational power has increased significantly. And, as Anonymous Coward mentioned on your thread, your system will not support a 50MHz bus, so you'd have to get a DX2/66 at best, which has a bus speed of 33MHz. On a system employing VLB graphics and I/O controller it's quite possible you could achieve something close to a 40% increase (according to this a 28% increase was measured between a DX/33 system and a similar DX2/66 system, but this did have local bus graphics).
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from what i can find in the net, prolinea 486 used "local bus" video. I would assume, something similar to VLB. Have not been able to find the exact chipset used, so just a guess.
this
http://www.totalgeekdom.com/wp-content/upload … rd-Close-up.jpg
shows TSENG ET4000/W32, so some sort of VLB. Decent chip!
wrote:this
http://www.totalgeekdom.com/wp-content/upload … rd-Close-up.jpg
shows TSENG ET4000/W32, so some sort of VLB. Decent chip!
Hah - I should have looked at the photos when I was reading that 😀
However, this says Tseng TC6945AF so I'm guessing there were a number of revisions of the motherboard so it depends which one the OP has. Either way, I think it's now safe to say that the graphics are local bus, so a CPU upgrade would indeed result in improved graphics performance 😀
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wrote:Hah - I should have looked at the photos when I was reading that 😀
However, this says Tseng TC6945AF so I'm guessing there were a number of revisions of the motherboard so it depends which one the OP has. Either way, I think it's now safe to say that the graphics are local bus, so a CPU upgrade would indeed result in improved graphics performance 😀
Agreed, it seemed to me that there were different revisions too. And yes, probably a faster CPU would be able to supply more data to the video card, it does look like a local bus one can benefit from that even on the same bus speed. 486DX-33 is definitely a bottleneck for a VLB TSENG 4000.
Yea, I recall that some onboard video was really fast on 486 machines. I recall a Dell that used a Cirrus Logic 542x chip on board, that came out as fastest in some test of 486es in a magazine at the time.
High-end 486 machines would probably use something closely related to VLB for their onboard video, since the VLB slot basically connects directly to the CPU bus anyway (much like how ISA was originally implemented on the 8088). All the control logic would already be in the video chipset they used (and they would use dedicated VRAM, unlike later onboard video, which uses shared system memory).
